Subarrays with K Different Integers

Given an array A of positive integers, call a (contiguous, not necessarily distinct) subarray of A good if the number of different integers in that subarray is exactly K.

(For example, [1,2,3,1,2] has 3 different integers: 1, 2, and 3.)

Return the number of good subarrays of A.

 

Example 1:

Input: A = [1,2,1,2,3], K = 2
Output: 7
Explanation: Subarrays formed with exactly 2 different integers: [1,2], [2,1], [1,2], [2,3], [1,2,1], [2,1,2], [1,2,1,2].

Example 2:

Input: A = [1,2,1,3,4], K = 3
Output: 3
Explanation: Subarrays formed with exactly 3 different integers: [1,2,1,3], [2,1,3], [1,3,4].

 

Note:

  1. 1 <= A.length <= 20000
  2. 1 <= A[i] <= A.length
  3. 1 <= K <= A.length

Solution:

class Solution {
    public int subarraysWithKDistinct(int[] A, int K) {
        int n = A.length;
        int left = 0, right = 0;
        int res = 0;
        Map<Integer, Integer> map = new HashMap();
        while (right < n) {
            int in = A[right];
            map.put(in, map.getOrDefault(in, 0) + 1);
            if (map.size() == K) {
                if (right == n - 1 || !map.containsKey(A[right + 1])) {
                    while (map.size() == K) {  
                        // System.out.println(map);
                        res ++;
                        int out = A[left];
                        map.put(out, map.get(out) - 1);
                        if (map.get(out) == 0) map.remove(out);
                        left ++;
                    } 
                } else {
                    int tempLeft = left;
                    Map<Integer, Integer> tempMap = new HashMap();
                    tempMap.putAll(map);
                    while (tempMap.size() == K) {  
                        // System.out.println(tempMap);
                        res ++;
                        int out = A[tempLeft];
                        tempMap.put(out, tempMap.get(out) - 1);
                        if (tempMap.get(out) == 0) tempMap.remove(out);
                        tempLeft ++;
                    }
                }
            }
            right ++;
        }
        return res;
    }
}